Field
This disclosure is generally related to the fabrication of a solar panel. More specifically, this disclosure is related to the fabrication of a solar panel with improved power output efficiency.
Related Art
The negative environmental impact of fossil fuels and their rising cost have resulted in a dire need for cleaner, cheaper alternative energy sources. Among different forms of alternative energy sources, solar power has been favored for its cleanness and wide availability.
A solar cell converts light into electricity using the photovoltaic effect. There are several basic solar cell structures, including a single p-n junction, p-i-n/n-i-p, and multi-junction. A typical single p-n junction structure includes a p-type doped layer and an n-type doped layer. Solar cells with a single p-n junction can be homojunction solar cells or heterojunction solar cells. If both the p-doped and n-doped layers are made of similar materials (materials with equal band gaps), the solar cell is called a homojunction solar cell. In contrast, a heterojunction solar cell includes at least two layers of materials of different bandgaps. A p-i-n/n-i-p structure includes a p-type doped layer, an n-type doped layer, and an intrinsic (undoped) semiconductor layer (the i-layer) sandwiched between the p-layer and the n-layer. A multi-junction structure includes multiple single-junction structures of different bandgaps stacked on top of one another.
In a solar cell, light is absorbed near the p-n junction generating carriers. The carriers diffuse into the p-n junction and are separated by the built-in electric field, thus producing an electrical current across the device and external circuitry. An important metric in determining a solar cell's quality is its energy-conversion efficiency, which is defined as the ratio between power converted (from absorbed light to electrical energy) and power collected when the solar cell is connected to an electrical circuit. High efficiency solar cells are essential in reducing cost to produce solar energies.
In practice, multiple individual solar cells are interconnected, assembled, and packaged together to form a solar panel, which can be mounted onto a supporting structure. Multiple solar panels can then be linked together to form a solar system that generates solar power. Depending on its scale, such a solar system can be a residential roof-top system, a commercial roof-top system, or a ground-mount utility-scale system. Note that, in such systems, in addition to the energy conversion efficiency of each individual cell, the ways cells are electrically interconnected within a solar panel also determine the total amount of energy that can be extracted from each panel. Due to the serial internal resistance resulted from the inter-cell connections an external load can only extra a limited percentage of the total power generated by a solar panel.